What papal bull granted Spain authority to appoint inquisitors in 1478?

The papal bull that granted Spain authority to appoint inquisitors in 1478 was Exigit sincerae devotionis affectus.

Pope Sixtus IV issued the bull on 1 November 1478. It authorized Ferdinand II of Aragon and Isabella I of Castile to select up to three bishops or other suitable churchmen to act as inquisitors in their territories. The immediate target was alleged secret adherence to Judaism among converts to Christianity, known as conversos.

This arrangement was significant because it placed the new tribunal under strong royal direction, unlike the more directly papal Medieval Inquisition. The first inquisitors appointed under the new system, Miguel de Morillo and Juan de San Martín, began work in 1480.

The title is often confused with other famous papal documents. Unam sanctam concerned papal authority and the Church; Ad extirpanda addressed the use of torture in inquisitorial proceedings; and In eminenti apostolatus was a much later bull associated with Jansenism. None established the Spanish Inquisition.